Enhanced mechanical and electrical properties of basalt fibers through alkaline treatment and electroless copper deposition

Basalt fibers (BFs) offer a sustainable alternative to conventional reinforcement materials, yet their inherent surface inertness limits their performance in advanced composites. Here, we demonstrate a novel approach to significantly enhance both the mechanical and electrical properties of BFs through controlled electroless copper (Cu) deposition facilitated by alkali pre-treatment. We reveal that potassium hydroxide (KOH) pre-treatment, compared to sodium hydroxide (NaOH), induces a specific surface modification on BFs, leading to improved Cu adhesion and uniform growth. This results in a 38 % increase in tensile strength (1766 ± 392 MPa at 50°C) compared to untreated BFs (1279 ± 301 MPa). Critically, the resulting Cu-coated BFs exhibit an electrical conductivity of 7.82 × 10⁷ S/m, surpassing that of commercial Cu (5.96 × 10⁷ S/m) and Ag (6.30 × 10⁷ S/m). At the optimal deposition temperature of 50°C, KOH-treated BFs achieved a density of 3.59 g/cm³ , significantly higher than the density of NaOH-treated BFs (3.26 g/cm³), but lower than that of Cu (8.96 g/cm³). The enhanced performance is attributed to the surface morphology induced by KOH, which promotes uniform Cu nucleation and growth. These findings establish KOH-treated, Cu-deposited BFs as promising candidates for high-performance composites, advanced electronics, and next-generation telecommunications, potentially enabling lighter, more efficient, and sustainable technologies for 5 G/6 G and beyond. A novel alkaline (KOH/NaOH)-mediated electroless copper deposition was employed on continuous basalt fibers, yielding significantly enhanced electrical conductivity exceeding that of commercial Cu and Ag, coupled with a substantial enhancement in tensile strength . This scalable process offers metallized fibers suitable for next-generation telecommunications. • Alkaline pre-treatment with Cu deposition enhanced BFs properties. • Cu-deposited BFs exhibited lower density (3.59 g/cm³) than Cu. • KOH pre-treated, Cu-deposited BFs showed higher conductivity (7.82 × 10⁷ S/m) than Cu and Ag. • KOH pre-treatment increased tensile strength to 1766 MPa (vs. 1695 MPa with NaOH). • Combined strength, low density, and high conductivity show significant potential.